Composite moulding materials

ABSTRACT

A composite moulding material ( 10 ) comprising a fibrous layer ( 12 ) and a graphene/graphitic material ( 14 ) applied to the fibrous layer ( 12 ) at one or more localised regions (R 1 , R 2 , R 3 , R 4 ) over a surface ( 16 ) of the fibrous layer ( 12 ) characterised in that the graphene/graphitic material ( 14 ) is comprised of graphene nanoplates, graphene oxide nanoplates, reduced graphene oxide nanoplates, bilayer graphene nanoplates, bilayer graphene oxide nanoplates, bilayer reduced graphene oxide nanoplates, few-layer graphene nanoplates, few-layer graphene oxide nanoplates, few-layer reduced graphene oxide nanoplates, graphene/graphitic nanoplates of 6 to 14 layers of carbon atoms, graphite flakes with nanoscale dimensions and 40 or less layers of carbon atoms, graphite flakes with nanoscale dimensions and 25 to 30 layers of carbon atoms, graphite flakes with nanoscale dimensions and 25 to 35 layers of carbon atoms, graphite flakes with nanoscale dimensions and 20 to 35 layers of carbon atoms, or graphite flakes with nanoscale dimensions and 20 to 40 layers of carbon atoms.

FIELD OF INVENTION

The present invention relates to composite moulding materials and in particular fibre reinforced composite moulding materials comprising graphene and or graphite and composite components made therefrom.

BACKGROUND

Fibre reinforced composites (FRC's) are widely used in many areas of manufacture, especially in the manufacture of high strength/lightweight structures, due to their relative light weight and high in-plane specific strength and stiffness characteristics.

FRC's typically have a laminate structure made up of a plurality of fibre reinforcement layers consolidated within a matrix resin. It is within the planes of the fibre reinforcement layers where the in-plane strength and stiffness is found. However, in comparison to the advantageous in-plane properties of FRC's, their out-of-plane (through-thickness) properties represent weakness, presenting vulnerability to delamination either from edges or as a result of external loads or damage and subsequent propagation, imperilling serviceability, overall integrity and potentially leading to catastrophic failure.

Various approaches have been made to improve resistance to such delamination in FRC's including stitching, Z-pinning, 3D weaving and insertion of toughening thermoplastic interleaves. However. all of these can have detrimental effects on in-plane mechanical properties.

It therefore remains a challenge to enhance fracture toughness and interlaminar strength to achieve improved fatigue performance without significant consequential detriment to in-plane strength or increase in weight.

STATEMENTS OF INVENTION

According to one aspect of the present invention there is provided a composite moulding material comprising a fibrous layer and a graphene/graphitic material applied to the fibrous layer at one or more localised regions over a surface of the fibrous layer in which the graphene/graphitic material is comprised of graphene nanoplates, graphene oxide nanoplates, reduced graphene oxide nanoplates, bilayer graphene nanoplates, bilayer graphene oxide nanoplates, bilayer reduced graphene oxide nanoplates, few-layer graphene nanoplates, few-layer graphene oxide nanoplates, few-layer reduced graphene oxide nanoplates, graphene/graphite nanoplates of 6 to 14 layers of carbon atoms, graphite flakes with nanoscale dimensions and 40 or less layers of carbon atoms, graphite flakes with nanoscale dimensions and 25 to 30 layers of carbon atoms, graphite flakes with nanoscale dimensions and 25 to 35 layers of carbon atoms, graphite flakes with nanoscale dimensions and 20 to 35 layers of carbon atoms, or graphite flakes with nanoscale dimensions and 20 to 40 layers of carbon atoms.

The graphene nanoplates, graphene oxide nanoplates, reduced graphene oxide nanoplates, bilayer graphene nanoplates, bilayer graphene oxide nanoplates, bilayer reduced graphene oxide nanoplates, few-layer graphene nanoplates, few-layer graphene oxide nanoplates, few-layer reduced graphene oxide nanoplates, graphene/graphite nanoplates of 6 to 14 layers of carbon atoms, graphite flakes with nanoscale dimensions and 40 or less layers of carbon atoms, graphite flakes with nanoscale dimensions and 25 to 30 layers of carbon atoms, graphite flakes with nanoscale dimensions and 20 to 35 layers of carbon atoms, graphite flakes with nanoscale dimensions and 25 to 35 layers of carbon atoms, or graphite flakes with nanoscale dimensions and 20 to 40 layers of carbon atoms are hereafter collectively referred to as “graphene/graphitic platelets”. Graphene, graphene oxide, and/or reduced graphene oxide nanoplates typically have a thickness of 1 to 10 layers of carbon atoms, typically between 0.3 nm and 3 nm, and lateral dimensions ranging from around 100 nm to 100 μm.

The graphene/graphitic material may be selectively located at at least one and preferably a plurality of predetermined regions over a surface of the fibrous layer.

The regions may be spaced and discrete.

The or each region may cover a surface area on the fibrous layer of between 0.001 mm² and 0.01 mm², 0.002 mm² and 0.01 mm², 0.01 mm² and 1.5 mm², between 0.01 mm² and 1.0 mm², between 0.5 mm² and 1.5 mm², and greater than 0.003 mm², greater than 0.5 mm² or greater than 1 mm².

The graphene/graphitic material at the, each or at least one of the region(s) may comprise a single body of material or may comprise a plurality of discrete bodies within the region(s).

The graphene/graphitic material may form one or more islands on the surface of the fibrous layer, the or each island preferably being surrounded by one or more areas of fibrous material deficient in graphene/graphitic material. That is where there is no graphene/graphitic material.

Each body may be one such island.

The graphene/graphitic material may be located at or in an array or pattern of regions over a surface of the fibrous layer.

The array or pattern may be regular, such as a regular array of bands, stripes, circles, spots, squares, blocks, columns, rows, or an array aligned along the nominal vertices of polyhedral shapes, for example hexagons, pentagons or other tessellating shapes.

Alternatively, the array may be irregular or may be regular in part and irregular in other part.

Bodies of graphene/graphitic material at the or at least one of the region(s) may comprise an array or pattern of graphene/graphitic material over a surface of the fibrous layer.

The array or pattern may be regular, such as a regular array of bands, stripes, circles, spots, squares, blocks, columns, rows, or an array aligned along the nominal vertices of polyhedral shapes, for example hexagons, pentagons or other tessellating shapes.

Alternatively, the array may be irregular or may be regular in part and irregular in other part.

The graphene/graphitic material may be located at one or more regions where the properties of the graphene/graphitic material will be beneficial to a composite component moulded from the composite moulding material.

The graphene/graphitic material may be a dispersion comprising graphene/graphite platelets dispersed in a carrier medium.

The graphene/graphitic platelets may comprise platelets comprising a plurality of layers of graphene/graphite and may have an average thickness of between 0.8 and 12 nanometres, may be between 1.3 and 9.4 nanometres and may be between 2.5 and 6 nanometres.

The graphene/graphitic platelets may comprise up to 25 or up to 35 layers of graphene, may be between 5 and 25 or 5 and 35 layers of graphene, and may be between 5 and 15 or 25 to 35 layers of graphene.

The graphene/graphitic platelets may comprise one or more of graphene, graphene oxide, reduced graphene oxide, graphite, graphite oxide, or reduced graphite oxide with a general plate-like (platelet) planar conformation.

The graphene/graphitic platelets may have a carbon content of between 40 wt % and 99 wt % and may be between 97 wt % and 99 wt % for platelets of graphene or graphite, may be between 80 wt % and 99 wt % for platelets of reduced graphene oxide or reduced graphite oxide, and may be between 40 wt % and 60 wt % by weight for platelets of graphene oxide or graphite oxide.

The graphene/graphitic platelets may have an sp2 content of between 40 wt % and 98 wt % and may be between 95 wt % and 98 wt % for platelets of graphene or graphite, may be between 60 wt % and 95 wt % for platelets of reduced graphene oxide or reduced graphite oxide and may be between 40 wt % and 60 wt % for graphene oxide or graphite oxide.

The graphene/graphitic platelets may comprise between 1 wt % and 50 wt % oxygen, may be between 1 wt % and 3 wt % oxygen for platelets of graphene or graphite, may be between 5 wt % and 10 wt % for platelets of reduced graphene oxide or reduced graphite oxide, and may be between 20 wt % and 50 wt % for platelets of graphene oxide or graphite oxide.

The graphene/graphitic platelets may have an average platelet size (planar dimension) of up to 40 μm, a d90 size of between 5 μm and 25 μm, a d90 size of between 1 μm and 40 μm, a d50 size of between 5 μm and 12 μm, and or a d50 size of between 1 μm and 30 μm. The particle sizes being measured using a Mastersizer 3000.

The graphene/graphitic platelets may comprise a plurality of layers of graphene, graphene oxide and/or reduced graphene oxide embedded in graphitic carbon.

The carrier medium may comprise resin, such as thermoset resin which may comprise one or more of epoxy, polyester (unsaturated), phenolic, vinyl ester, polyurethane, silicone, polyamide, polyamideimide, bismaleimide, cyanate ester, benzoxazine.

Alternatively or in addition, the carrier medium may comprise thermoplastic resin which may comprise one or more of polyethylene (PE), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycarbonate (PC), acrylonitrile butadiene styrene (ABS), polyamide (PA or nylon) and polypropylene (PP). High-performance thermoplastic resins—polyetheretherketone (PEEK), polyetherketone (PEK), polyamide-imide (PAI), polyarylsulfone (PAS), polyetherimide (PEI), polyethersulfone (PES), polyphenylene sulphide (PPS).

Alternatively or in addition, the carrier medium may comprise biobased resins which may comprise one or more of starch, starch caprolactone blends, polyesters—polyalkylene succinates, polyesteramides, polyhydroxy alkanoates—polyvinyl butyral—polyvinyl valeate, polyhydroxy acids—polylacticacid—polyglycolic acid, cellulose acetate, furfural alcohol/furan resins, oil modified polyesters—vegetable oil modification—cashew nut oil modification.

Alternatively or in addition, the carrier medium may comprise deionised water and/or solvent, which may comprise one or more of hexane, benzene, toluene, xylene, diethylether, 1,4-dioxane, ethyl acetate, nbutyl acetate, t-butyl acetate, ethyl ethoxy propionate, propyleneglycol monomethyl ether acetate, methyl acetate, dimethylcarbonate, tetrahydrofuran, dichloromethane, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl propyl ketone, methyl isoamyl ketone, acetonitrile, dimethlyformamide, dimethylsluphoxide, n-butanol, methanol, ethanol, n-propanol, isopropanol, butanol, glycols-ethylene glycol, propylene glycol, parachlorobenzotrifluoride.

The carrier medium may be the same as or otherwise compatible with resin in the fibrous layer.

The dispersion may have a graphene/graphitic material content in the range 0.001 wt % to 10 wt %, 0.001 wt % to 1 wt %, 0.01 wt % to 0.5 wt %, 0.01 wt % to 5 wt %.

The area density of graphene/graphitic material applied to the fibrous layer may be in the range 1 mg/m² to 35000 mg/m², 1 mg/m² to 2000 mg/m², 10 mg/m² to 100 mg/m², 1000 mg/m² to 20000 mg/m², 1000 mg/m² to 10000 mg/m², or 10 mg/m² to 20 mg/m².

The dispersion may have a viscosity in the range 1 to 75 centipoise, 1 to 50 centipoise, 10 to 50 centipoise, approximately 20 centipoise, or approximately 15 centipoise as measured at 10 γ·(s−1)@23° C.

The graphene/graphite material is preferably applied to the fibrous layer by a selective application process such as ink jet printing, including one or more of thermal drop on demand and a piezo drop on demand ink jet printing, valve jet printing, contact printing, non-contact printing, by spray techniques or by use of a mask and spray methods.

The graphene/graphitic material may be applied in droplets and the inter-droplet spacing may be between 0.01 mm and 0.5 mm or between 0.3 mm and 2 mm.

The graphene/graphitic material may be applied in any manner that enables selective application for the accurate location of the graphene/graphitic material at one or more selected regions across the surface of the fibrous layer, the said region(s) may be preselected as being at or anticipated to lie at stressed or potentially stressed locations within a composite component moulded from the composite moulding material.

The fibrous layer may comprise fibrous material partially or fully impregnated with curable matrix resin and may be in the form of one or more of a prepreg, a partially cured prepreg, an uncured fibrous preform, a partially cured fibrous preform.

The fibrous layer may comprise one or more plies of fibrous material.

Alternatively or in addition, the fibrous layer may comprise, at least in part, dry fibrous material.

The fibrous material may comprise one or more forms of fibrous reinforcing materials for fibre reinforced composites, including one or more of woven mat, unwoven mat, continuous fabric, unidirectional fabric, braided fabric, knitted fabric, woven fabric, discontinuous mat, chopped fibres, 3D woven materials, single fibre tow, unidirectional prepreg, slit tape prepreg, tow prepreg.

The fibrous material may comprise one or more of carbon fibres, glass fibres, aramid fibres, plastic fibres, nylon fibres, terylene fibres, hemp fibres, wood fibres and/or other organic fibres or inorganic fibres.

The curable matrix resin of the fibrous layer may comprise resin, such as thermoset resin which may comprise one or more of epoxy, polyester (unsaturated), phenolic, vinyl ester, polyurethane, silicone, polyamide, polyamideimide, bismaleimide, cyanate ester, benzoxazine.

Alternatively or in addition, the curable matrix resin of the fibrous layer comprises thermoplastic resin which may comprise one or more of polyethylene (PE), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycarbonate (PC), acrylonitrile butadiene styrene (ABS), polyamide (PA or nylon) and polypropylene (PP). High-performance thermoplastic resins—polyetheretherketone (PEEK), polyetherketone (PEK), polyamide-imide (PAI), polyarylsulfone (PAS), polyetherimide (PEI), polyethersulfone (PES), polyphenylene sulphide (PPS).

Alternatively or in addition, the curable matrix resin of the fibrous layer may comprise biobased resins which may comprise one or more of starch, starch caprolactone blends, polyesters—polyalkylene succinates, polyesteramides, polyhydroxy alkanoates—polyvinyl butyral-polyvinyl valeate, polyhydroxy acids—polylacticacid—polyglycolic acid, cellulose acetate, furfuralalcohol/furan resins, oil modified polyesters—vegetable oil modification—cashew nut oil modification.

The carrier may be the same resin as, substantially the same as, or otherwise compatible with the curable matrix resin.

The fibrous layer may comprise a laminate structure, which may comprise a plurality of plies of fibrous material, in which the fibrous material and/or the curable matrix resin may be the same or may differ between the plies.

The composite moulding material may comprise one or more outer layers that may cover any otherwise externally exposed graphene/graphitic material in the composite moulding material.

The outer layer(s) may comprise a fibrous layer.

According to a further aspect of the present invention there is provided a moulding laminate comprising a plurality of layers of composite moulding material as described in any of the preceding paragraphs.

The composite moulding material may be the same in some and preferably all of the layers.

Alternatively, the composite moulding material may differ between layers and each layer may be different to all other layers within the moulding laminate.

The layers of composite moulding material may be laminated, one on top of the other.

The layers may be laminated so that graphene/graphitic material on at least one or some of the layers is aligned or substantially aligned with graphene/graphitic material on at least one other layer within the moulding material in the out-of-plane direction. The out of plane direction being a direction approximately perpendicular to the plane of the layer or layers at the position of the graphene/graphitic material being considered.

The layers may be laminated so that some or all of the graphene/graphitic material on adjacent layers or on at least two adjacent layers is superimposed or substantially superimposed in the out-of-plane direction.

Alternatively, layers may be laminated so that graphene/graphitic material on adjacent layers is misaligned or substantially misaligned or at least some of the graphene/graphitic material on adjacent layers is misaligned or substantially misaligned between those layers.

The moulding laminate may comprise one or more outer laminate layers that may cover any otherwise externally exposed graphene/graphitic material in the moulding laminate.

The outer laminate layer(s) may be the same or substantially the same as a fibrous layer of composite moulding material in the moulding laminate.

According to a still further aspect of the present invention there is provided a fibre reinforced composite component comprising a plurality of fibrous layers held within a cured matrix resin and graphene/graphitic material at one or more localised regions between at least two of the fibrous layers to provide interlaminar fracture toughness at said region(s).

According to a yet further aspect of the present invention there is provided a method of manufacturing a composite moulding material, the method comprising providing a fibrous layer and applying a graphene/graphitic dispersion at one or more localised regions over a surface of the fibrous layer in which the graphene/graphitic dispersion comprises graphene nanoplates, graphene oxide nanoplates, reduced graphene oxide nanoplates, bilayer graphene nanoplates, bilayer graphene oxide nanoplates, bilayer reduced graphene oxide nanoplates, few-layer graphene nanoplates, few-layer graphene oxide nanoplates, few-layer reduced graphene oxide nanoplates, graphene/graphite nanoplates of 6 to 14 layers of carbon atoms, graphite flakes with nanoscale dimensions and 40 or less layers of carbon atoms, graphite flakes with nanoscale dimensions and 25 to 30 layers of carbon atoms, graphite flakes with nanoscale dimensions and 25 to 35 layers of carbon atoms, graphite flakes with nanoscale dimensions and 20 to 35 layers of carbon atoms, or graphite flakes with nanoscale dimensions and 20 to 40 layers of carbon atoms.

It will be understood that the graphene/graphitic dispersion is a liquid that can be applied to a fibrous layer. Once applied the dispersion may become solid or at least a liquid of higher viscosity so forming the graphene/graphitic material. The process by which the dispersion becomes the material is dependent on the nature of the dispersion and may include, but not be limited to, evaporation of a solvent, chemical reaction, or thermo-chemical reaction.

The graphene/graphitic dispersion may be selectively applied to at least one and preferably a plurality of predetermined regions over a surface of the fibrous layer.

The graphene/graphitic dispersion may be selectively applied to spaced and discrete regions.

The graphene/graphitic dispersion may be selectively applied so that the or each region may cover a surface area on the fibrous layer of between 0.01 and 1.5 mm², between 0.01 mm² and 1.0 mm², between 0.5 mm² and 1.5 mm², and typically of greater than 0.5 mm² or greater than 1 mm².

The graphene/graphitic dispersion may be selectively applied so that the graphene/graphitic dispersion at the, each or at least one of the region(s) may comprise a single body of material or may comprise a plurality of discrete bodies within the region(s).

The graphene/graphitic dispersion may be selectively applied so that the graphene/graphitic dispersion may form one or more islands on the surface of the fibrous layer, the or each island preferably being surrounded by one or more areas of fibrous material deficient in graphene/graphite.

The graphene/graphitic dispersion may be applied at or in an array or pattern of localised regions over a surface of the fibrous layer.

The graphene/graphitic dispersion may be applied as a regular array or pattern, such as a regular array of bands, stripes, circles, spots, squares, blocks, columns, rows, or an array aligned along the nominal vertices of polyhedral shapes, for example hexagons, pentagons or other tessellating shapes.

Alternatively, the graphene/graphitic dispersion may be applied as an irregular array or pattern, or as an array or pattern regular in part and irregular in other part.

Bodies of graphene/graphitic dispersion at the or at least one of the region(s) may be applied as an array or pattern of graphene/graphitic dispersion over a surface of the fibrous layer.

The array or pattern may be regular, such as a regular array of bands, stripes, circles, spots, squares, blocks, columns, rows, or an array aligned along the nominal vertices of polyhedral shapes, for example hexagons, pentagons or other tessellating shapes.

Alternatively, the array may be irregular or may be regular in part and irregular in other part.

The graphene/graphitic dispersion may be applied at one or more regions where the properties of the graphene/graphitic material will be beneficial to a composite component moulded from the composite moulding material.

The graphene/graphitic dispersion may comprise graphene/graphitic platelets dispersed in a carrier medium.

The graphene/graphitic platelets may comprise platelets comprising a plurality of layers of graphene and may have an average thickness of between 0.8 and 12 nanometres, between 1.3 and 9.4 nanometres and may be between 2.5 and 6 nanometres.

The graphene/graphitic platelets may comprise up to 25 or up to 35 layers of graphene, may be between 5 and 25 or 5 and 35 layers of graphene, and may be between 5 and 15 or 25 to 35 layers of graphene.

The graphene/graphitic platelets may comprise one or more of graphene, graphene oxide, reduced graphene oxide, graphite, graphite oxide, reduced graphite oxide with a generally plate-like (platelet) conformation.

The graphene/graphitic platelets may have a carbon content of between 40 wt % and 99 wt % and may be between 97 wt % and 99 wt % for platelets of graphene or graphite, may be between 80 wt % and 99 wt % for platelets of reduced graphene oxide or reduced graphite oxide, and may be between 40 wt % and 60 wt % by weight for platelets of graphene oxide or graphite oxide.

The graphene/graphitic platelets may have an sp2 content of between 40 wt % and 98 wt % and may be between 95 wt % and 98 wt % for platelets of graphene or graphite, may be between 60 wt % and 95 wt % for platelets of reduced graphene oxide or reduced graphite oxide and may be between 40 wt % and 60 wt % for graphene oxide or graphite oxide.

The graphene/graphitic platelets may comprise between 1 wt % and 50 wt % oxygen, may be between 1 wt % and 3 wt % oxygen for platelets of graphene or graphite, may be between 5 wt % and 10 wt % for platelets of reduced graphene oxide or reduced graphite oxide, and may be between 20 wt % and 50 wt % for platelets of graphene oxide or graphite oxide.

The graphene/graphitic platelets may have an average platelet size (planar dimension) of up to 40 μm, a d90 size of between 5 μm and 25 μm, a d90 size of between 1 μm and 40 μm, a d50 size of between 5 μm and 12 μm, and or a d50 size of between 1 μm and 30 μm. The particle sizes being measured using a Mastersizer 3000.

The graphene platelets may comprise a plurality of layers of graphene, graphene oxide and/or reduced graphene oxide embedded in graphitic carbon.

The carrier medium used may comprise resin, such as thermoset resin which may comprise one or more of epoxy, polyester (unsaturated), phenolic, vinyl ester, polyurethane, silicone, polyamide, polyamideimide, bismaleimide, cyanate ester, benzoxazine.

Alternatively or in addition, the carrier medium may comprise thermoplastic resin which may comprise one or more of polyethylene (PE), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycarbonate (PC), acrylonitrile butadiene styrene (ABS), polyamide (PA or nylon) and polypropylene (PP). High-performance thermoplastic resins—polyetheretherketone (PEEK), polyetherketone (PEK), polyamide-imide (PAI), polyarylsulfone (PAS), polyetherimide (PEI), polyethersulfone (PES), polyphenylene sulphide (PPS).

Alternatively or in addition, the carrier medium may comprise biobased resins which may comprise one or more of starch, starch caprolactone blends, polyesters—polyalkylene succinates, polyesteramides, polyhydroxy alkanoates polyvinyl butyral—polyvinyl valeate, polyhydroxy acids—polylacticacid—polyglycolic acid, cellulose acetate, furfuralalcohol/furan resins, oil modified polyesters—vegetable oil modification—cashew nut oil modification

Alternatively or in addition, the carrier medium may comprise deionised water and/or solvent, such as one or more of hexane, benzene, toluene, xylene, diethylether, 1,4-Dioxane, ethyl acetate, nbutyl acetate, t-butyl acetate, ethyl ethoxy propionate, propyleneglycol monomethyl ether acetate, methyl acetate, Dimethylcarbonate, tetrahydrofuran, Dichloromethane, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl propyl ketone, methyl isoamyl ketone, Acetonitrile, Dimethlyformamide, dimethylsluphoxide, n-butanol, methanol, ethanol, n-propanol, isopropanol, butanol, glycols-ethylene glycol, propylene glycol, parachlorobenzotrifluoride.

The carrier medium used may be the same as or otherwise compatible with resin in the fibrous layer.

The dispersion may have a graphene/graphitic platelet content in the range 0.001 wt % to 10 wt %, 0.001 wt % to 1 wt %, 0.01 wt % to 0.5 wt %, 0.01 wt % to 5 wt %.

The area density of graphene/graphitic dispersion applied to the fibrous layer may be in the range 1 mg/m² to 35000 mg/m², 1 mg/m² to 2000 mg/m², 10 mg/m² to 100 mg/m², 1000 mg/m² to 20000 mg/m², 1000 mg/m² to 10000 mg/m², or 10 mg/m² to 20 mg/m².

The dispersion may have a viscosity in the range 1 to 75 centipoise, 1 to 50 centipoise, 10 to 50 centipoise, approximately 20 centipoise, or approximately 15 centipoise as measured at 10 γ·(s−1)@23° C.

The graphene/graphitic dispersion is preferably applied to the fibrous layer by a selective application process such as ink jet printing, including one or more of thermal drop on demand and a piezo drop on demand ink jet printing, valvejet printing, contact printing, non-contact printing, by spray techniques or by use of a mask and spray methods.

The graphene/graphitic dispersion may be applied in droplets and the inter-droplet spacing may be between 0.01 mm and 0.5 mm or between 0.3 mm and 2 mm.

The graphene/graphitic dispersion may be applied in any manner that enables selective application for the accurate location of the graphene/graphitic material at one or more selected regions across the surface of the fibrous layer, the said region(s) may be preselected as being or anticipated to lie at stressed or potentially stressed locations within a composite component moulded from the composite moulding material.

The fibrous layer provided may comprise fibrous material partially or fully impregnated with curable matrix resin and may be in the form of one or more of a prepreg, a partially cured prepreg, an uncured fibrous preform, a partially cured fibrous preform.

The fibrous layer provided may comprise one or more plies of fibrous material.

Alternatively or in addition, the fibrous layer provided may comprise, at least in part, dry fibrous material.

The fibrous material used may comprise one or more forms of fibrous reinforcing materials for fibre-reinforced composites, including one or more of woven mat, unwoven mat, continuous fabric, unidirectional fabric, braided fabric, knitted fabric, woven fabric, discontinuous mat, chopped fibres, 3D woven materials, single fibre tow, unidirectional prepreg, slit tape prepreg, tow prepreg.

The fibrous material used may comprise one or more of carbon fibres, glass fibres, aramid fibres, plastic fibres, nylon fibres, terylene fibres, hemp fibres, wood fibres and/or other organic fibres or inorganic fibres.

The curable matrix resin of the fibrous layer may comprise resin, such as thermoset resin which may comprise one or more of epoxy, polyester (unsaturated), phenolic, vinyl ester, polyurethane, silicone, polyamide, polyamideimide, bismaleimide, cyanate ester, benzoxazine.

Alternatively or in addition, the curable matrix resin of the fibrous layer comprises thermoplastic resin which may comprise one or more of polyethylene (PE), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycarbonate (PC), acrylonitrile butadiene styrene (ABS), polyamide (PA or nylon) and polypropylene (PP). High-performance thermoplastic resins—polyetheretherketone (PEEK), polyetherketone (PEK), polyamide-imide (PAI), polyarylsulfone (PAS), polyetherimide (PEI), polyethersulfone (PES), polyphenylene sulphide (PPS).

Alternatively or in addition, the curable matrix resin of the fibrous layer may comprise biobased resins which may comprise one or more of starch, starch caprolactone blends, polyesters—polyalkylene succinates, polyesteramides, polyhydroxy alkanoates—polyvinyl butyral-polyvinyl valeate, polyhydroxy acids—polylacticacid—polyglycolic acid, cellulose acetate, furfuralalcohol/furan resins, oil modified polyesters—vegetable oil modification—cashew nut oil modification

The carrier used may be the same resin as, substantially the same as, or otherwise compatible with the curable matrix resin.

The fibrous layer provided may comprise a laminate structure, which may have a plurality of plies of fibres, in which the fibrous material and/or the curable matrix resin may be the same or may differ between the plies.

One or more outer layers may be provided to cover any otherwise externally exposed graphene/graphite material in the composite moulding material.

The outer layer(s) provided may comprise a fibrous layer.

According to a further aspect of the present invention there is provided a method of manufacturing a moulding laminate, the method comprising laminating a plurality of composite moulding materials as described above.

The composite moulding material used may be the same in some and preferably all of the layers.

Alternatively, the composite moulding material used may differ between layers and each layer may be different to all other layers within the moulding laminate.

The layers of composite moulding material may be laminated one on top of the other.

The layers may be laminated so that graphene/graphitic material on at least some of the layers is aligned or substantially aligned with graphene/graphitic material on at least one other layer within the moulding material.

The layers may be laminated so that some or all of the graphene/graphitic material on adjacent layers is superimposed or substantially superimposed in the out-of-plane direction.

Alternatively, layers may be laminated so that graphene/graphitic material on adjacent layers is misaligned or substantially misaligned or at least some of the graphene/graphitic material on adjacent layers is misaligned or substantially misaligned between those layers.

One or more outer laminate layers may be provided that may cover any otherwise externally exposed graphene/graphitic material in the moulding laminate.

The outer laminate layer(s) used may be the same or substantially the same as a fibrous layer of composite moulding material in the moulding laminate.

According to another aspect of the present invention there is provided a method of manufacturing a fibre reinforced composite component, the method comprising providing a plurality of fibrous layers, a curable matrix resin to consolidate the fibrous layers and applying a graphene/graphitic dispersion at one or more localised regions over a surface of at least one of the fibrous layers, positioning the fibrous layers so that the graphene/graphitic material is located between two adjacent fibrous layers and subjecting the component to conditions to cure the matrix resin around the fibrous material.

EXAMPLE

To demonstrate the benefit of composite moulding materials according to the present invention a specimen composite material was made using an inkjet application of graphite material.

An ink for use in an inkjet printer was prepared as follows:

The required amounts of xylene, an epoxy resin (commercially available under the name BP012 from SHD Composite Materials Ltd, UK) and graphene/graphitic platelets were mixed.

The inks were made to the formulations shown in Table 1.

TABLE 1 A-GNP BP012 resin Xylene Sample Ref A-GNP (wt. %) (wt. %) (wt. %) Unprinted N/A N/A N/A N/A Control Ink 1 A-GNP10 0.1 20 79.9 Ink 2 A-GNP30 0.1 20 79.9 Ink 3 A-GNP35(T) 0.1 20 79.9 Ink 4 (control - None 0 20 80 resin + solvent) Ink 5 (control - None 0 0 100 solvent only)

Graphene/graphitic material A-GNP10 is commercially available from Applied Graphene Materials UK Limited, UK and comprises graphite platelets of between 25 and 35 layers of atoms thick).

Graphene/graphitic material A-GNP30 is commercially available from Applied Graphene Materials UK Limited, UK and comprises graphite platelets of between 3 and 6 layers of atoms thick).

Graphene/graphitic material A-GNP35(T) is commercially available from Applied Graphene Materials UK Limited, UK and comprises graphite platelets of between 6 and 12 layers of atoms thick).

Printing of the ink formulations onto a plie was performed using a Microfab Jetlab 4xl inkjet printer using 60 μm nozzle, a deposition rate of approximately 30 Hz, and a dot spacing of 0.28 mm. The graphite material coverage was as set out in Table 2.

Sample panels were manufactured in the following fashion:

12 plies were layed up in a unidirectional fashion with a 0° orientation. The printed plie being used as the 6^(th) plie in the layup and the printed region was located adjacent a release film laid on the surface pf the printed plie. The release film is used to initiate an interlaminar crack in the desired position in the sample.

The sample was then pressure cured with a cure temperature profile which includes a ramp rate of 1° C./min to 120° C., followed by a 1 hour dwell at 120° C., and at a pressure of 600 kPa (6 Bar).

The samples were then tested for mode-I fracture toughness (crack propagation) (G1c) using the ASTM-5528 standard method and British Standard ISO 15024:2001 using Shimdazu EZ-LX 1 kN testing equipment at 25° C.

The results of the testing were as shown in Table 3

TABLE 2 In flight A-GNP droplet Droplet Ink Droplet Mass A-GNP Droplets/m² A-GNP Area Sample loading diameter volume Density mass within droplet (0.28 mm density on prepreg Ref. (wt. %) (μm) (cm³) (mg/cm³) (mg) (mg) spacing) (mg/m²) Unprinted N/A N/A N/A N/A N/A N/A N/A N/A Control 1 0.1 50 6.545E−08 900 5.890E−05 5.890E−08 1.276E+07 0.751 2 0.1 50 6.545E−08 902 5.904E−05 5.904E−08 1.276E+07 0.753 3 0.1 50 6.545E−08 901 5.897E−05 5.897E−08 1.276E+07 0.752 4 control - 0 50 6.545E−08 904.6 5.921E−05 0.000E+00 1.276E+07 0.000 resin + solvent 5 control - 0 50 6.545E−08 905.2 5.925E−05 0.000E+00 1.276E+07 0.000 solvent only

BRIEF DESCRIPTION OF DRAWINGS

Preferred embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a diagrammatic perspective of a composite material according to the present invention;

FIG. 2 is a diagrammatic perspective of a composite material according to another embodiment of the present invention;

FIG. 3 is a diagrammatic perspective of a composite material according to a further embodiment of the present invention;

FIG. 4 is a diagrammatic perspective of a composite material according to another embodiment of the present invention;

FIG. 5 is a diagrammatic perspective of a composite material according to a further embodiment of the present invention;

FIG. 6 is a diagrammatic perspective of a composite material according to another embodiment of the present invention;

FIG. 7 is a diagrammatic perspective of a composite material according to a further embodiment of the present invention;

FIG. 8 is a diagrammatic cross-sectional view of a composite moulding material according to a still further embodiment of the present invention;

FIG. 9a is a diagrammatic perspective view of a moulding laminate according to the present invention;

FIG. 9b is a diagrammatic cross-section along the line IXb of FIG. 9 a;

FIG. 10a is a diagrammatic perspective view of a moulding laminate according to a further embodiment of the present invention;

FIG. 10b is a diagrammatic cross-section of the moulding laminate of FIG. 10a along the line X13,

FIG. 11 is a diagrammatic cross-section of a further moulding laminate according to a further embodiment of the present invention;

FIG. 12 is a diagrammatic cross-section of a fibre reinforced composite component according to the present invention;

FIG. 13 is a diagrammatic cross-section of two fibre reinforced composite components according to the present invention, secured by a fastener F; and

FIG. 14 is a diagrammatic cross-section of the moulding laminate of FIG. 10a , being moulded.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The invention provides a composite moulding material comprising a fibrous layer and a graphene/graphitic material applied to the fibrous layer at one or more localised regions on a surface of the fibrous layer.

FIG. 1 illustrates one embodiment of a composite moulding material 10 which has a fibrous layer 12 and a graphene/graphitic material 14 applied to the fibrous layer 12 at four localised regions R1, R2, R3, R4 over the surface 16 of the fibrous layer 12.

The graphene/graphitic material 14 has been selectively applied at each of the predetermined regions R1, R2, R3, R4 on the surface 16 of the fibrous layer 12.

In the particular embodiment illustrated in FIG. 1, each of the four predetermined regions R1, R2, R3, R4 is located generally in a respective corner of the surface 16 of the fibrous layer 12. The regions R1, R2, R3, R4 are spaced from each other to provide discrete bodies of graphene/graphitic material 14. In the embodiment illustrated in FIG. 1 a single body of graphene/graphitic material 14 is provided in each region R1, R2, R3, R4.

The amount of graphene/graphitic material applied to the fibrous layer in a given region is determined according to a number of factors, including the nature of the graphene/graphitic material itself, the nature of the fibrous layer, the nature of any moulding laminate to be produced using the composite moulding material, the desired properties and characteristics, in particular interlaminar toughness and strength characteristics, required or sought for composite components to be formed using the composite moulding material.

By way of example, the graphene/graphitic material 14 in each region R1, R2, R3, R4 may cover a surface on the fibrous layer of between 0.01 and 1.5 mm² in certain embodiments, between 0.5 mm² and 1.5 mm² in other embodiments, between 0.01 mm² and 1.0 mm² in other embodiments, greater than 0.5 mm², or greater than 1 mm². The area covered may be considerably greater than 1 mm² if appropriate/required.

Each body of graphene/graphitic material 14 in the embodiment of FIG. 1 forms an island of graphene/graphitic material on the surface of the fibrous layer 12 and each island is surrounded by fibrous material deficient in graphene/graphite.

In the embodiment of FIG. 1 the graphene/graphitic material 14 is located in a regular array or pattern of regions with R1, R2, R3, R4 being aligned along the nominal vertices of a quadrilateral.

FIG. 2 illustrates a composite moulding material according to a further embodiment, where features that are the same or equivalent to features in embodiment of FIG. 1 have the same reference numeral but prefixed with a ‘1’. In relation to other embodiments described herein that have the same or equivalent features, these are referenced with the same numeral but with a respective prefix number.

In the embodiment of FIG. 2 the graphene/graphitic material 114 has been applied in two localised regions R1, R2, which are generally in the form of a simple pattern of two bands or stripes that extend across the surface 116 and generally parallel both mutually and to the sides of the fibrous layer 112 of the composite moulding material 210.

The graphene/graphitic material can be applied in any number of regions or configuration of regions and those regions may form a regular array or pattern over the surface of the fibrous layer, such as regular arrays or patterns of bands, strips, circles, spots, squares, blocks, columns, rows, and/or any array or pattern aligned along the nominal vertices of polyhedral shapes, for example hexagons, pentagons or other tessellating shapes.

In certain embodiments the graphene/graphitic material is provided at localised, preselected and predetermined regions that between them define an irregular pattern or array.

FIG. 3 illustrates one such exemplary embodiment, where graphene/graphitic material 214 is provided as an irregular pattern or array of regions R1, R2, R3, R4, R5 on the surface 216 of the fibrous layer 212 of the composite moulding material 310.

In further embodiments the graphene/graphitic material is applied to the surface of the fibrous layer in an array or pattern that in part is regular and in other part is irregular.

An illustrated example of such embodiments is shown in FIG. 4, where the regions R1, R2, R3, R4 provide a regular part of the array or pattern and R5, R6, R7 represent an irregular part.

Within the scope of the present invention, the graphene/graphitic material can be applied at any configuration of localised regions on the surface of the fibrous layer and an advantage of the present invention is that it allows materials to be engineered that provide for the advantageous characteristics and properties of the graphene/graphitic material, and in particular the graphene/graphitic within the material to be realised in a selective and predetermined manner, which in turn enables a number of related advantages to be realised, as will be discussed.

It is often the case that there are particular areas or zones within composite components made using laminated fibre reinforced composites where the typical interlaminar weaknesses are or are more likely than elsewhere in the components to become problematic and the present invention provides for the selective application of graphene/graphitic material at predetermined localised regions within composite moulding materials that can be used to produce such composite components to allow composite components to be engineered such that graphene/graphitic material is present in those areas or zones, thus affording the composites the improved interlaminar fracture toughness and strength characteristics that the graphene/graphite material provides, precisely where needed and not elsewhere, where not needed.

This ability to precisely engineer composites in this way has a number of benefits.

First of all, it naturally allows for the precise placement of the graphene/graphite platelets only where really needed, which has efficiencies of cost and other manufacturing efficiencies.

It helps to avoid adding unnecessary weight, helps avoid or reduce processing problems and costs such as viscosity/particle agglomeration seen when incorporating high specific surface area nanomaterials in making intermediates such as formulated resins, films, prepreg tapes, etc. It can also facilitate or enable the use of lower viscosity and cost effective resins to impregnated fibres under lower consolidating pressures and/or quicker cycle times, reducing levels of waste or scrappage. It can help reduce the negative impact on other mechanical or physical properties and can enable existing materials and/or structural designs to be upgraded without the need for a process or design overhaul.

The precision placement of the graphene/graphitic material into the interlaminar boundary will enhance fracture toughness through crack bridging and deflection mechanisms. It is expected that this will result in a reduction in crack growth and an improvement in composite designs under fatigue. The improved fracture toughness at the interlaminar boundary enhances the performance of composite and enables a change in composite design methodologies. The use of such graphene/graphite platelet modified materials should enable composite structures to be developed to the same safety design considerations of today but with a smaller number of composite layers resulting in significant benefits in materials used and weight of the composite component.

In certain embodiments bodies of graphene/graphitic material are provided within a region and the bodies comprise an array or pattern of graphene/graphitic material on a surface of the fibrous layer, within a zone.

FIG. 5 illustrates one such embodiment in a composite moulding material 410, where three discrete bodies B1, B2, B3 of graphene/graphitic material 414 are provided in each region R1, R2, R3, R4.

The regions R1, R2, R3, R4 are in a mutually regular pattern and the bodies B1, B2, B3 within each region are likewise in a mutually regular pattern. In this particular embodiment in FIG. 5, the bodies B1, B2, B3 are each a strip that run mutually parallel within the respective region R1, R2, R3, R4.

In other embodiments the pattern or array of bodies of graphene/graphitic material within the region or one or more of the regions are otherwise regular, such as regular arrays or patterns of bands, circles, spots, squares, blocks, columns, rows, or any array aligned along the nominal vertices of polyhedral shapes, for example hexagons, pentagons or other tessellating shapes.

In other embodiments the bodies within a region are applied in an array or pattern that is irregular, as illustrated by the bodies B1, B2, B3 in the composite moulding material 510 embodied in FIG. 6.

In other embodiments one or more of the regions are regular and the bodies within the other or at least one of the other regions are irregular.

An illustrative example of a moulding material 610 according to such an embodiment is shown in FIG. 7, where the bodies B1, B2, B3 of graphene/graphitic material 614 in region R1 are in an irregular pattern or array and the bodies B1, B2, B3 of graphene/graphitic material 614 in region R2 are in a regular array of three mutually parallel strips or lines on the surface 612.

The graphene/graphitic material comprises a dispersion of graphene/graphite platelets dispersed in a carrier medium.

The graphene/graphite platelets comprise plate-like particles or platelets that comprise a plurality of layers of graphene (monolayer), each platelet having a general thickness (measured through the thickness of the platelets, generally perpendicularly across the plane of the platelet) of between 0.8 and 12 nanometres in certain embodiments, of between 1.3 and 9.4 nanometres in other embodiments, and of between 2.5 and 6.0 nanometres in still further embodiments.

Graphene/graphite platelets that have been found to have particular utility in the present invention comprise up to 25 layers or up to 35 layers of graphene/graphite. In certain embodiments, the graphene/graphite platelets have between 5 and 25 or 5 and 35 layers of graphene/graphite and in other embodiments between 5 and 15 or 25 and 35 layers of graphene/graphite.

In certain embodiments the graphene/graphite platelets have a carbon content of between 40% and 99% by weight, although the chemical content will vary according to the composition of the platelets.

It is found that graphene/graphite platelets with an sp2 content of between 60% and 98% have particular utility in the present invention, although again the sp2 content will vary according to the composition of the platelets.

Typically, the oxygen content of the graphene/graphite platelets is between 1% and 50%, varying according to the composition of the platelets.

The table 5 shows the typical percentage carbon content, sp2 content and percentage oxygen, by weight, of platelets of graphene, reduced graphene oxide and graphene oxide.

TABLE 5 Reduced Graphene Graphene Graphene Oxide Oxide % carbon 97-99 80-99 40-60 sp² content 98-95 60-95 40-60 % oxygen 1-3  5-10 20-50

In particular embodiments of the present invention the graphene/graphitic platelets may have an average platelet size (planar dimension) of up to 40 μm, a d90 size of between 5 μm and 25 μm, a d90 size of between 1 μm and 40 μm, a d50 size of between 5 μm and 12 μm, and or a d50 size of between 1 μm and 30 μm. The particle sizes being measured using a Mastersizer 3000.

The graphene platelets may comprise one or more of graphene, graphene oxide and reduced graphene oxide, which is typically embedded in graphitic carbon.

In certain embodiments the carrier medium comprises thermoset resin which comprises one or more of epoxy, polyester (unsaturated), phenolic, vinyl ester, polyurethane, silicone, polyamide, polyamideimide, bismaleimide, cyanate ester, benzoxazine.

In other embodiments the carrier medium comprises thermoplastic resin, which in certain embodiments is selected from one or more of polyethylene (PE), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycarbonate (PC), acrylonitrile butadiene styrene (ABS), polyamide (PA or nylon) and polypropylene (PP). High-performance thermoplastic resins—polyetheretherketone (PEEK), polyetherketone (PEK), polyamide-imide (PAI), polyarylsulfone (PAS), polyetherimide (PEI), polyethersulfone (PES), polyphenylene sulphide (PPS).

In certain embodiments the carrier medium comprises biobased resins which can comprise one or more of starch, starch caprolactone blends, polyesters—polyalkylene succinates, polyesteramides, polyhydroxy alkanoates—polyvinyl butyral-polyvinyl valeate, polyhydroxy acids—polylacticacid—polyglycolic acid, cellulose acetate, furfuralalcohol/furan resins, oil modified polyesters—vegetable oil modification—cashew nut oil modification

The carrier medium can comprise deionised water and/or solvent, such as one or more of hexane, benzene, toluene, xylene, diethylether, 1,4-Dioxane, ethyl acetate, nbutyl acetate, t-butyl acetate, ethyl ethoxy propionate, propyleneglycol monomethyl ether acetate, methyl acetate, Dimethylcarbonate, tetrahydrofuran, Dichloromethane, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl propyl ketone, methyl isoamyl ketone, Acetonitrile, Dimethlyformamide, dimethylsluphoxide, n-butanol, methanol, ethanol, n-propanol, isopropanol, butanol, glycols-ethylene glycol, propylene glycol, parachlorobenzotrifluoride

In certain embodiments the carrier medium comprises one or more of thermoset resin, thermoplastic resin, bio-based resin, solvent and water.

In preferred embodiments the carrier medium is compatible with the resin in the fibrous layer and in certain embodiments the carrier medium is the same as resin in the fibrous layer.

In certain embodiments the dispersion has a graphene/graphite platelet content in the range of 0.001 wt % to 10 wt %, 0.001 wt % to 1 wt %, by weight, may be in the range 0.01 wt % to 0.5 wt %, 0.01 wt % to 5 wt % by weight.

In certain embodiments the area density of graphene/graphitic material applied to the fibrous layer is in the range 1 mg/m² to 35000 mg/m², 1 mg/m² to 2000 mg/m², 10 mg/m² to 100 mg/m², 1000 mg/m² to 20000 mg/m², 1000 mg/m² to 10000 mg/m², or 10 mg/m² to 20 mg/m².

In certain embodiments the dispersion, particularly at the time of application, has a viscosity in the range 1 to 75 centipoise, 1 to 50 centipoise, 10 to 50 centipoise, approximately 20 centipoise, or approximately 15 centipoise In such embodiments the dispersion typically comprises approximately 20% by weight of resin, with solvent, such as xylene or any of the other solvent carriers described herein.

In other embodiments the viscosity of the dispersion is in the range 0.9 to 50 centipoise, and in such embodiments the dispersion is typically resin free or substantially resin free, with the graphene/graphite platelets dispersed in a non-resinous carrier medium such as solvent, one being xylene, or any of the others described herein.

Viscosities discussed in connection with the present invention are as measured on a Malvern Kinexus rheometer at 10 γ·(s−1)@23° C.

The graphene/graphitic material is of a viscosity that enables it to be applied to the fibrous layer by a selective application process such as ink jet printing, including one or more of thermal drop on demand and piezo drop on demand ink jet printing, valvejet printing, contact printing, non-contact printing, by any other suitably selective and accurate spray technique or by use of a mask and spray method.

A particularly favoured application process for the present invention is ink jet printing, as this enables selective application for the accurate location of the graphene/graphitic material at the predetermined localised region or regions on the surface of the fibrous layer.

The graphene/graphitic material can be applied in a single stage of printing, or in a multiple stage printing process.

It has been found that applying the graphene/graphitic material as droplets with inter-droplet spacing of between 0.01 mm and 0.5 mm has particular utility in the present invention. Such printing of the graphene/graphitic material at predetermined and localised region(s), in predetermined patterns or arrays of regions or within regions as described above enables precise and accurate deposition and provision of graphene/graphitic material in composites, enabling precise engineering of composite moulding materials and the onward engineering of moulding laminates and composite components made from such composite mouldings, within which the graphene/graphitic material is localised where delamination is anticipated or considered a notable probability, where stresses are known, anticipated or considered a notable probability or otherwise where considered advantageous, within a composite component moulded from the composite moulding material, thus providing precise and localised benefit to be realised as a result of the presence of the graphene/graphitic material, including improved strength and interlaminar toughness.

In certain embodiments the fibrous layer of the composite moulding material comprises fibrous material partially or fully impregnated with curable matrix resin.

In certain embodiments the fibrous layer comprises an uncured prepreg, a partially cured prepreg, an uncured fibrous preform or a partially cured fibrous preform.

In certain embodiments the fibrous layer comprises one ply of fibrous material and in other embodiments comprises a plurality of plies of fibrous material.

In certain embodiments the fibrous layer comprises dry fibrous material (without any associated resin) and in other embodiments comprises one or more plies of dry fibrous material and one or more plies of fibrous material preimpregnated with resin.

The fibrous material of the composite moulding materials of the present invention can be known formats of fibre reinforcement typically used for fibre reinforced composites, including one or more of woven mat, unwoven mat, continuous fabric, unidirectional fabric, braided fabric, knitted fabric, woven fabric, discontinuous mat, chopped fibres, single fibre tow, impregnated slit tape, 3D woven materials, unidirectional prepreg, slit tape prepreg, tow prepreg.

The fibrous material can comprise any suitable organic and/or inorganic fibre and in certain embodiments can comprise one or more of carbon fibres, glass fibres, aramid fibres, plastic fibres, nylon fibres, terylene fibres, hemp fibres, wood fibres.

In certain embodiments the curable matrix resin of the fibrous layer comprises thermoset resin, which can be selected from one or more of epoxy, polyester (unsaturated), phenolic, vinyl ester, polyurethane, silicone, polyamide, polyamideimide, bismaleimide, cyanate ester, benzoxazine.

In other embodiments, the curable matrix resin of the fibrous layer comprises thermoplastic resin, which can be selected from one or more of polyethylene (PE), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycarbonate (PC), acrylonitrile butadiene styrene (ABS), polyamide (PA or nylon) and polypropylene (PP). High-performance thermoplastic resins—polyetheretherketone (PEEK), polyetherketone (PEK), polyamide-imide (PAI), polyarylsulfone (PAS), polyetherimide (PEI), polyethersulfone (PES), polyphenylene sulphide (PPS).

The curable matrix resin of the fibrous layer can comprise biobased resins such as one or more of starch, starch caprolactone blends, polyesters—polyalkylene succinates, polyesteramides, polyhydroxy alkanoates—polyvinyl butyral-polyvinyl valeate, polyhydroxy acids—polylacticacid—polyglycolic acid, cellulose acetate, furfural alcohol/furan resins, oil modified polyesters—vegetable oil modification—cashew nut oil modification

In certain embodiments the curable matrix resin is the same, substantially the same or otherwise compatible with the carrier medium of the graphene material.

In certain embodiments the fibrous layer comprises a laminate structure, which comprises a plurality of plies of fibrous material.

In certain embodiments the fibrous material is the same between laminates and in other embodiments the fibrous material can be different between laminates.

FIG. 8 is a diagrammatic cross-section of one exemplary embodiment of a composite moulding material 710 that has a laminate structure made up of three plies P1, P2, P3 of fibrous materials impregnated with an uncured resinous material that holds the plies together. Graphene/graphitic material 714 is shown on the surface 716 of the fibrous layer 712 at two localised regions R1, R2.

In certain embodiments an outer layer (not shown) is provided over the surface 716 to cover and typically to protect the graphene/graphitic material 714 applied to the surface 716. The outer layer is typically removed prior to cure, although in certain embodiments it remains during the cure process and can become part of the cured composite component.

The invention also provides moulding laminates comprising a plurality of layered composite moulding materials as described above.

FIGS. 9a and 9b illustrate one embodiment of a moulding laminate 18 comprising three laminated layers of composite moulding material 810A, 810B, 810C.

The composite moulding materials 810A, 810B, 810C are the same and the layers are laminated directly one on top of the other so that bodies of the graphene/graphitic material 814A, 814B, 814C in the respective layers are aligned on top of each other in the direction through generally (perpendicular to) the plane of the layers.

In an alternative embodiment the composite moulding materials differ between layers, and in certain embodiments each layer is different to all other layers within the moulding laminate.

In such embodiments the location of the graphene/graphitic material can still be at the same region on the respective layers, such that when laminated the graphene/graphitic material can be in alignment, generally as illustrated in FIGS. 9a and 9b , despite the differences between in particular the fibrous layer in each composite moulding material.

In still further embodiments, the same or differing layers may be laminated so that the bodies of graphene/graphitic material on at least some of the layers are not in alignment.

FIGS. 10a and 10b illustrate a moulding laminate 118 that comprises three layers of composite material 910A, 910B, 910C, wherein composite moulding materials 910A and 910C are the same and the bodies of graphene/graphitic material 914A, 914C are generally aligned in the direction generally perpendicular to (through) the plane of the layers, and the intermediate layer 910B has a differing or offset pattern or array of graphene/graphitic material 910B to those on composite moulding materials 910A, 910C.

Such embodiments provide differing locations of graphene/graphitic material, and thus locations of toughening and strengthening through the thickness of the laminate.

In certain embodiments an outer laminate layer is provided to cover graphene/graphitic material that would otherwise be exposed on the outer surface of the stack of layers.

FIG. 11 shows the composite moulding materials of FIGS. 10a and 10b with such an outer laminate layer 20.

In certain embodiments the outer laminate layer 20 is the same as the fibrous layer of one or all of the composite moulding materials of the moulding laminate.

In other embodiments the outer laminate layer is of a different material, such as a protective or release sheet or film.

It will be clear to those skilled in the art that the configuration, conformation and composition of the composite moulding materials and the moulding laminate can be engineered, using the precision and flexibility provided by the present invention in the selective and localised application of the graphene/graphitic material to enable a huge range of materials to be engineered that have precise, predetermined and localised strengthening and toughening, in particular interlaminar strength and toughening.

As described herein, the fibrous material of the composite moulding materials of the present invention can be of many known forms and almost unlimited shapes and sizes, the primary limitations being that the materials are of a handleable and processable size and present a surface on which graphene/graphitic material can be applied to the fibrous layer at one or more localised regions over that surface. So for example, the material can be in the form of a sheet or ply, a 3D preform, a tape, a tow.

The invention also provides a fibre reinforced composite component comprising a plurality of fibrous layers held within a cured matrix resin and graphene/graphitic material at one or more localised regions between at least two of the fibrous layers to provide interlaminar fracture toughness of said region(s).

FIG. 12 illustrates one embodiment of a fibre reinforced composite component 22 that comprises four fibrous layers 1012A, 1012B, 1012C,1012D, consolidated within a matrix resin with graphene/graphitic material 1014A, 1014B, 1014C located between each of the four fibrous layers 1012A, 1012B, 1012C, 1012D at a generally central region within the component.

The presence of the graphene/graphitic material 1014A, 1014B, 1014C provides for interlaminar fracture toughness where it is located and in the embodiment shown in FIG. 12 the alignment of graphene/graphitic material 1014A, 1014B, 1014C in the direction through the thickness of the component 22 provides a central region of improved toughness extending through the thickness of the component 22.

This through-thickness interlaminar toughness provides precise, localised beneficial physical characteristics to the component 22.

This can have a number of advantages and uses, one of which is to provide for increased strength and toughness for mechanical fixings or fastenings to pass centrally through the central region (as illustrated) of the fibre reinforced composite component 22.

FIG. 13 is a diagrammatic illustration of a mechanical fastening F, such as a rivet, bolt or similar, that passes through the illustrated central region of two fibre reinforced composite components 22, to fasten them together.

Without the presence of the graphene/graphitic material at the location where the fastening passes through the components 22, as the fastening F is driven through the components or as the bore is drilled to accommodate the fastening F, there is significant risk of interlaminar damage and fatigue in conventional fibre reinforced composites.

The provision of the graphene/graphitic material in accordance with the present invention provides for improved interlaminar fracture toughness and resistance to such interlaminar delamination and crack propagation and thus provides components with improved, yet localised toughness and resistance to delamination.

It will be appreciated that, for example, that where a series of fasteners is required to fasten composite components together or to otherwise pass through a composite component, then in accordance with the present invention the composite moulding materials, the moulding laminates and the fibre reinforced composite components can be engineered through the selective, predetermined and precise localised provision of graphene/graphitic material at the locations where the fasteners are to be used, provides improved interlaminar toughness and strength in a specific, precise, cost effective and otherwise advantageous manner.

The present invention also provides a method of manufacturing a fibre reinforced composite component, the method comprising providing a plurality of fibrous layers, a curable matrix resin to consolidate the fibrous layers and applying a graphene/graphitic dispersion at one or more localised regions over a surface of at least one of the fibrous layers, positioning the fibrous layers so that the graphene/graphitic material is located between two adjacent fibrous layers and subjecting to conditions to cure the matrix resin around the fibrous material.

Known techniques and processes for forming fibre reinforced components can be used as part of the manufacturing method of the present invention. For example, manual and automated lay-up of plies of fibrous layers, vacuum moulding, autoclave moulding, fibre placement, pultrusion, tape laying, etc can be used.

FIG. 14 is a diagrammatic illustration of a simple vacuum moulding process used to form a composite component from the moulding laminate 118 of FIG. 10b . The laminate 118 is sealed on the surface of a mould M, beneath an impermeable membrane IM. Air from beneath the membrane IM is drawn out, shown diagrammatically by the arrow A, as heat is applied to the laminate to consolidate the laminate and cure the matrix resin.

It will be appreciated that processes of this nature are particularly suitable for moulding composite moulding materials of particular (generally sheet-like) conformations.

Processes such as filament winding, tape laying and pultrusion can be used for moulding composite moulding materials of the present invention in the form of tows or tapes and can be used to mould composite moulding materials according to the present invention.

It will be appreciated that in accordance with the present invention, the graphene/graphitic material can be applied to a fibrous layer that is preimpregnated with resin, or to a dry fibrous layer (not preimpregnated with resin) or, within certain embodiments, of composite laminate according to the present invention, to both.

Techniques and processes for moulding preimpregnated fibrous materials and dry fibrous materials (eg resin transfer) are well known to those in the art and it will be understood that such techniques and processes can be used in the context of the present invention.

It will be appreciated that moulding laminates can be provided according to the present invention by layering any number of the same or different combinations of composite moulding materials falling within the scope of this invention, either in partial, total or non-alignment, and the nature of alignment may vary between respective layers in multilayer laminates.

Various modifications may be made without departing from the spirit or scope of the present invention. For example, the composite moulding material with a moulding laminate may be layered so that the orientation of respective composite moulding materials may be varied, such as alternated between successive layers, so that the respective surface carrying the graphene/graphitic material alternate through the structure, enabling graphene/graphite material on adjacent layers to contact when aligned.

Features described in the preceding description may be used in combinations other than the combinations explicitly described. Although functions can be described with reference to certain features, those functions may be performable by other features, whether described or not. Although features have been described with reference to certain embodiments, those embodiments may also be present in other embodiments, whether described or not.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance, it should be understood that the applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings, whether or not particular emphasis has been placed thereon. 

1. A composite moulding material comprising a fibrous layer and a graphene/graphitic material applied to the fibrous layer at one or more localised regions over a surface of the fibrous layer, the graphene/graphitic material comprising graphene nanoplates, graphene oxide nanoplates, reduced graphene oxide nanoplates, bilayer graphene nanoplates, bilayer graphene oxide nanoplates, bilayer reduced graphene oxide nanoplates, few-layer graphene nanoplates, few-layer graphene oxide nanoplates, few-layer reduced graphene oxide nanoplates, graphene/graphite nanoplates of 6 to 14 layers of carbon atoms, graphite flakes with nanoscale dimensions and 40 or less layers of carbon atoms, graphite flakes with nanoscale dimensions and 25 to 30 layers of carbon atoms, graphite flakes with nanoscale dimensions and 25 to 35 layers of carbon atoms, graphite flakes with nanoscale dimensions and 20 to 35 layers of carbon atoms, or graphite flakes with nanoscale dimensions and 20 to 40 layers of carbon atoms.
 2. The composite moulding material according to claim 1, in which the graphene/graphitic material is selectively located at at least one predetermined region over the surface of the fibrous layer.
 3. The composite moulding material according to claim 1, in which the localised regions are spaced and discrete from each other.
 4. The composite moulding material according to claim 1, in which at least one said region covers a surface area on the fibrous layer of between 0.01 mm² and 1.5 mm², between 0.01 mm² and 1.0 mm², between 0.5 mm² and 1.5 mm², greater than 0.5 mm², or greater than 1 mm².
 5. The composite moulding material according to claim 1, in which the graphene/graphitic material is located at or in an array or pattern of regions over the surface of the fibrous layer.
 6. The composite moulding material according to claim 5, in which the array or pattern is a regular array, an irregular array, or an array which is regular in part and irregular in other part.
 7. The composite moulding material according to claim 1, in which the graphene/graphitic material comprises platelets comprising a plurality of layers of graphene/graphitic and having an average thickness of between 0.8 and 12 nanometres, between 1.3 and 9.4 nanometres, or between 2.5 and 6 nanometres.
 8. The composite moulding material according to claim 1, in which the graphene/graphitic material comprises platelets of up to 25 layers of graphene, up to 35 layers of graphene, between 5 and 25 layers of graphene, between 5 and 35 layers of graphene, between 5 and 15 layers of graphene, or between 25 to 35 layers of graphene.
 9. The composite moulding material according to claim 1, in which the graphene/graphitic material comprises a carrier medium comprising one of a resin, a thermoset resin, an epoxy resin, a polyester (unsaturated) resin, a phenolic resin, a vinyl ester resin, a polyurethane resin, a silicone resin, a polyamide resin, a polyamideimide resin, a bismaleimide resin, a cyanate ester resin, a benzoxazine resin, a thermoplastic resin, a polyethylene (PE) resin, a polyethylene terephthalate (PET) resin, a polybutylene terephthalate (PBT) resin, a polycarbonate (PC) resin, an acrylonitrile butadiene styrene (ABS) resin, a polyamide (PA or nylon) resin, a polypropylene (PP) resin, a high-performance thermoplastic resin, a polyetheretherketone (PEEK) resin, a polyetherketone (PEK) resin, a polyamide-imide (PAI) resin, a polyarylsulfone (PAS) resin, a polyetherimide (PEI) resin, a polyethersulfone (PES) resin, a polyphenylene sulphide (PPS) resin, a biobased resin, a biobased resin comprising starch, a biobased resin comprising a starch caprolactone blend, a biobased resin comprising polyesters, a biobased resin comprising a polyalkylene succinate, a biobased resin comprising a polyesteramide, a biobased resin comprising a polyhydroxy alkanoate, a biobased resin comprising a polyvinyl butyral, a biobased resin comprising a polyvinyl valeate, a biobased resin comprising a polyhydroxy acid, a biobased resin comprising a polylactic acid, a biobased resin comprising a polyglycolic acid, a biobased resin comprising a cellulose acetate, a biobased resin comprising a furfural alcohol, a biobased resin comprising a furan resin, a biobased resin comprising an oil modified polyester, a biobased resin comprising a vegetable oil modification, a biobased resin comprising a cashew nut oil modification, deionised water, a solvent, hexane, benzene, toluene, xylene, di ethyl ether, 1,4-Dioxane, ethyl acetate, nbutyl acetate, t-butyl acetate, ethyl ethoxy propionate, propyleneglycol monomethyl ether acetate, methyl acetate, dimethyl carbonate, tetrahydrofuran, Dichloromethane, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl propyl ketone, methyl isoamyl ketone, Acetonitrile, dimethlyformamide, dimethylsluphoxide, n-butanol, methanol, ethanol, n-propanol, isopropanol, butanol, glycols-ethylene glycol, propylene glycol, parachlorobenzotrifluoride, or a mixture or combination of two or more of the aforesaid.
 10. The composite moulding material according to claim 1, in which the graphene/graphitic material has a graphene/graphite content in the range 0.001 wt % to 10 wt %, 0.001 wt % to 1 wt %, 0.01 wt % to 0.5 wt %, or 0.01 wt % to 5 wt %.
 11. The composite moulding material according to claim 1, in which graphene/graphitic material applied to the fibrous layer has an area density in the range of 1 mg/m² to 2000 mg/m², 10 mg/m² to 100 mg/m², 1000 mg/m² to 20000 mg/m², 1000 mg/m² to 10000 mg/m², or 10 mg/m² to 20 mg/m².
 12. A moulding laminate comprising a plurality of layers of the composite moulding material according to claim
 1. 13. The moulding laminate according to claim 12, in which each of the layers are the same as each other, each of the layers are different from each other, or at least two of the layers are the same as each other.
 14. The moulding laminate according to claim 12, in which the graphene/graphitic material on at least one of the layers is aligned or substantially aligned with the graphene/graphitic material on at least one other layer within the moulding material in the out of plane direction.
 15. The moulding laminate according to claim 12, in which the graphene/graphitic material on adjacent layers or on at least two adjacent layers is superimposed or substantially superimposed in the out-of-plane direction.
 16. A fibre reinforced composite component comprising a plurality of fibrous layers held within a cured matrix resin and graphene/graphitic material at one or more localised regions between at least two of the fibrous layers to provide interlaminar fracture toughness at said region(s).
 17. The fibre reinforced composite component according to claim 16, in which at least one of the fibrous layers is the composite moulding material according to claim
 1. 18. A method of manufacturing the composite moulding material according to claim 1, the method comprising providing a fibrous layer and applying a graphene/graphitic dispersion at one or more localised regions over a surface of the fibrous layer in which the graphene/graphitic dispersion comprises graphene nanoplates, graphene oxide nanoplates, reduced graphene oxide nanoplates, bilayer graphene nanoplates, bilayer graphene oxide nanoplates, bilayer reduced graphene oxide nanoplates, few-layer graphene nanoplates, few-layer graphene oxide nanoplates, few-layer reduced graphene oxide nanoplates, graphene/graphitic nanoplates of 6 to 14 layers of carbon atoms, graphite flakes with nanoscale dimensions and 40 or less layers of carbon atoms, graphite flakes with nanoscale dimensions and 25 to 30 layers of carbon atoms, graphite flakes with nanoscale dimensions and 25 to 35 layers of carbon atoms, graphite flakes with nanoscale dimensions and 20 to 35 layers of carbon atoms, or graphite flakes with nanoscale dimensions and 20 to 40 layers of carbon atoms.
 19. The method of manufacturing a composite moulding material according to claim 18, in which the graphene/graphitic dispersion is applied to the fibrous layer by a selective application process.
 20. The method of manufacturing a composite moulding material according to claim 18, in which the graphene/graphitic dispersion is applied in droplets having inter-droplet spacing between 0.01 mm and 0.5 mm or between 0.3 mm and 2 mm.
 21. The composite moulding material according to claim 1, in which the graphene/graphitic dispersion has a viscosity in the range 1 to 75 centipoise, 1 to 50 centipoise, 10 to 50 centipoise, approximately 20 centipoise, or approximately 15 centipoise as measured at 10 γ·(s−1)@23° C.
 22. A method of manufacturing a fibre reinforced composite component, the method comprising providing a plurality of fibrous layers and a curable matrix resin to consolidate the fibrous layers, applying a graphene/graphitic dispersion at one or more localised regions over a surface of at least one of the fibrous layers, positioning the fibrous layers so that the graphene/graphitic material resultant from the dispersion is located between two adjacent fibrous layers, and subjecting the component to conditions to cure the matrix resin around the fibrous material. 